These years, an introduction of wind turbine generators is increasing remarkably, and in order to enhance economy through increasing capacity of a single machine, a demand of a small size and large capacity permanent magnet type electric power generator is increasing. However, when reducing the size and increasing the capacity of a permanent magnet type electric power generator is tried, since the amount of heat generated is increased, a permanent magnet type electric power generator as shown in FIG. 11 has been proposed.
Namely, the permanent magnet type generator is constituted in a sealed structure by covering a rotor 2 fixed to a rotating shaft 1 and a stator 3 arranged around the circumference of the rotor 2 via an air gap with a housing 4, and is provided with a heat exchanger 5 at the outer circumferential side of the stator 3. In this heat exchanger 5, a plurality of cooling pipes 14 are disposed along the extending direction of the rotating shaft 1, and a motor driven fan 15 is disposed at the exhaust side of the cooling pipes 14 for flowing outer air a through the cooling pipes 14.
By means of such permanent magnet type generator provided with the heat exchanger 5, inner gas (air or cooling wind) b of raised temperature that has cooled such as the rotor 2 and the stator 3 while circulating inside the housing 4 can be cooled by causing to flow through inside the heat exchanger 5 thereby to suppress a possible increase of an amount of heat generated.
A related technology that suppresses a possible increase of an amount of heat generated by passing inner air circulating in the machine through a heat exchanger is disclosed in patent document 1.
Patent Document 1: JP-A-2-70247